Entamoeba histolytica, a protozoan parasite, is an important human pathogen. Diseases caused by E. histolytica include dysentery and liver abscesses, and this organism is a leading parasitic cause of death on a global scale. The life cycle of Entamoeba involves stage inter-conversion between trophozoites and cysts. Importantly, the conversion to cysts allows the pathogen to disseminate to new hosts while development to trophozoites allows the organism to cause invasive disease in the host. Thus, stage interconversion is essential for disease transmission and pathogenesis. However, despite being central to amebic biology, stage conversion is poorly understood. Many factors have contributed to the paucity of data including the inability to reproduce the developmental cycle in E. histolytica. Instead, the reptilian ameba E. invadens, which has the same disease pathogenesis as E. histolytica, has been used as a model system to study Entamoeba development. In E. invadens, both encystation and excystation can be recapitulated with high efficiency in vitro. However, until recently a poorly annotated genome and lack of methods for genetic manipulation have prevented full exploitation of this system. The recent re-sequencing of the E. invadens genome, publication of the transcriptome of stage conversion, and development of methods for constitutive and regulated gene expression open up new avenues for discovery. We aim to build upon these recent successes by studying transcription factors that regulate stage conversion as a means to identify pathways that regulate encystation. We will (i) characterize two known transcription factors to determine their roles in controlling stage conversion, and (ii) identify a new transcription factor that controls genes regulated during early encystation. These data will allow us to gain the first insights into the molecular mechanisms that regulate Entamoeba development and could give important insights into methods for blocking this transition or new targets for therapeutics. Dissecting the developmental cascade is crucial to understanding the biology of this important human pathogen.